The present invention relates generally to indoor air-quality systems and more particularly to the operation of indoor air-quality systems with ultraviolet light sources.
Some known indoor air-quality systems include ultraviolet photocatalytic oxidation devices which remove gases such as volatile organic compounds from the air in heating ventilation and air-conditioning systems. These devices include ultraviolet light sources that direct ultraviolet light onto a photocatalyst on a substrate. The ultraviolet light sources must be replaced periodically, thus increasing the cost of maintaining the device. The more that the ultraviolet light sources are on, the more frequently they will have to be replaced.
In some installations, the ultraviolet light sources must be downstream of the air-conditioning evaporator coil. When the evaporator coil is activated, the air downstream is cold. Ultraviolet light sources are less effective when cold, so additional ultraviolet light sources are sometimes required when they are installed downstream of the evaporator coil.